1. Field of the Invention
The present invention relates to a technology for forming a two-dimensional image using a one-dimensional display device having light emitting sections or light modulating sections disposed in a predetermined direction in correspondence to a one-dimensional pixel line. This technology can be applied to, for example, an image display apparatus (projector apparatus) for projecting an image on a screen in a magnified form.
2. Description of the Related Art
There have been proposed and commercially used various kinds of arrangements of a projector apparatus for projecting an image in a magnified form using a two-dimensional display device such as a liquid crystal light valve and the like and using a projecting system.
In recent years, high resolution is increasingly required to introduce a new broadcasting system, to improve an image processing speed in step with an advance of an arithmetic operation device, and to convert a conventional mode for projecting an image in a magnified form using a film (so-called analog cinema) into a mode utilizing digital signal processing (digital cinema).
However, it is difficult for the two-dimensional display device to keep pace with the tendency for high resolution because of the drawbacks thereof resulting from an increase in the number of pixels and miniaturization of a pixel size.
When it is intended to achieve high resolution by, for example, increasing the (total) number of pixels while fixing a size of a display device, an open portion of a display cannot help being reduced, thereby brightness is sacrificed (it is difficult to realize a bright projector apparatus). In contrast, when it is intended to achieve high resolution while fixing a pixel size, a drawback occurs in that a size of a display device is indispensably increased, from which an apparatus including an optical system is increased in size and made expensive.
Note that a reduction in a pixel size requires a countermeasure for preventing smaller foreign substances from being mixed into the display device in a manufacturing process thereof. Further, an increase in size of the display device requires to increase a size of a manufacturing apparatus itself.
Thus, when there is employed an arrangement for executing scanning in a predetermined direction using a one-dimensional display device, it is possible to greatly reduce the number of pixel trains of the device.
As an example, when a two-dimensional display device is used in an very fine television or an advanced television, that is, a so-called high definition television, the number of sections as many as 2,070,000 pixels (≈1920×1080), whereas, in a system in which scanning is executed in a horizontal (H) direction using a one-dimensional display device, the high definition television can be realized by the number of elements as large as 108,000 pixels, from which it is apparent that the one-dimensional display device is superior to the two-dimensional display device.
A grating light valve (GLV) of Silicon Light Machines, U.S.A., for example, is known as the one-dimensional display device (refer to U.S. Pat. No. 5,311,360). Note that the grating light valve is composed of a phase reflection type diffraction grating formed by making best use of a technology for a micro electromechanical system (MEMS).
When the grating light valve is used as a one-dimensional light modulating device together with an illuminating light system for irradiating light to the grating light valve, diffraction gratings constituting respective pixels can be mechanically operated based on an image signal, and the grating light valve can be acted as a image display device by controlling a phase difference of light resulting from the operation of the diffraction gratings. In this case, an image can be formed by using a Schlieren optical system as an optical system in order to separate ± first order diffracted light and zero order diffracted light from the diffraction gratings constituting the respective pixels and to cut off one of the diffracted light (off light).
When a projector optical system is employed in a display apparatus with a large screen using the one-dimensional display device, a projection lens is provided with the one-dimensional display device and a light deflection device is provided to deflect the light passing through the lens as shown in U.S. Pat. No. 5,982,553, National Publication No. 2000-513114, and the like. That is, after a one-dimensional intermediate image from the one-dimensional display device is projected in a magnified form by the projection lens, a two-dimensionally projected image can be obtained on a screen by optically scanning the projected image by a light deflection device disposed at the pupil position of the projection lens or in the periphery thereof.
However, in the conventional arrangement, the following problems arise as to an increase in size, complexity, and the like of the apparatus.
For example, a size of the projection lens is increased because the pupil position of the projection lens, which projects the one-dimensional intermediate image in a magnified form, is disposed at a position apart from the lens to reduce a load on the light deflection device. Further, when a variable power function is added to the projection lens, a scanning angle must be changed in correspondence to variable power, which will make a system arrangement complex.
In addition to the above mentioned, problems resulting from the conventional arrangement will arise in strain of an image. For example, in a system arranged such that a position of an image projected onto a screen can be adjusted by, for example, shifting an optical axis of a projection lens with respect to the one-dimensional intermediate image, significant strain is caused by the shift of the optical axis. Further, when a projecting distance is short as in a back surface projecting apparatus (so-called rear projector) and the like, an adverse effect due distortion is increased as well as out of focus occurs on the screen, thereby image quality is deteriorated.
Accordingly, an object of the present invention is to fulfill a requirement for high resolution by using a one-dimensional display device and to realize a light scanning apparatus and a two-dimensional image forming apparatus which are less expensive and small in size.